The FK506 binding protein 51 kDa (FKBP51) (Sinars et al., 2003) (Genbank Accession Nos. AAC51189.1 and AAC86983.1) is an important co-chaperone of the heat shock protein 90 kDa (Hsp90) machinery. Single nucleotide polymorphisms (SNPs) in FKBP5, the gene coding for FKBP51, can lead to elevated levels of FKBP51 and susceptibility to major depression, post-traumatic stress disorder (PTSD), and anxiety disorders. Furthermore, FKBP51 levels increase with age and are further elevated in the brains of Alzheimer's disease (AD) patients. These findings have called attention to FKBP51, with growing efforts being directed at discovering potential therapeutic compounds to inhibit the protein. Unfortunately there are no current treatments available that target this protein. FKBP51 exhibits functional control of stress hormone receptors, most notably the glucocorticoid receptor (GR), decreasing affinity of glucocorticoids for the receptor and preventing its nuclear translocation (Stechschulte et al., 2014).